The present invention relates to a powder apparatus for a printing press which blows powder to the printing surface of a sheet, so that undried ink will not cause setoff between sheets stacked on a pile plate in the delivery unit of the printing press.
A powder apparatus of this type for a printing press is disclosed in Japanese Utility Model Registration No. 2578195 (reference 1). The apparatus disclosed in reference 1 has a spray for blowing powder to the printing surface of a sheet which is conveyed as it is held by the grippers of delivery chains, shielding members provided upstream and downstream of the spray in the sheet convey direction to prevent the powder from scattering, and brushes provided to the shielding members and each brought into slidable contact with the grippers of the delivery chains. In this arrangement, the powder blown from the spray toward the printing surface of the sheet is shielded by the shielding members and brushes, so it is prevented from scattering around.
In the conventional powder apparatus described above, as each brush is fixed to the corresponding shielding member, when the grippers pass through the brush, the brush is not retreated from the grippers. In this case, if the brush is positioned to come into contact with the grippers entirely, it may interfere with the grippers from traveling, and when it comes into slidable contact with the grippers, the bristles may be pulled out and scatter. For this reason, the brush can be brought into slidable contact with only part of the grippers, and accordingly can be brought close to the sheet held by the distal ends of the grippers only limitedly. A comparatively large gap is thus formed between the distal end of the brush and a paper guide that supports the sheet under conveyance. The powder may desirably scatter around through this gap.
It is an object of the present invention to provide a powder apparatus for a printing press which prevents powder scattering.
In order to achieve the above object, according to the present invention, there is provided a powder apparatus for a printing press, comprising sheet conveying means having sheet holding means for holding and moving in a sheet convey direction a sheet having a printing surface, powder spraying means for spraying powder toward the printing surface of the sheet which is being conveyed by the sheet conveying means, and a circular columnar rotary member provided downstream of the powder spraying means in the sheet convey direction and supported rotatably, the rotary member having at least one notch that opposes the sheet holding means, during rotation, which moves along with sheet convey operation.